I came across a good piece of writing from John Flavel called "Method of Grace". In one of his chapters he examines the reason for our being called "new creation". The phrase invites comparison to the first creation of Genesis 1. Some of these points below were from Flavel. I think that works like his are very helpful for Christians. It is just such a shame that there is a barrier between us and these Puritan writers; their language is kind of slow going, yet there is often such profundity in their insights.

I believe that one of the best ways for us to grow in wisdom and knowledge of God and in discernment is not so much to argue and convince others as it is to just spend so much time and focus in God's Word that we instinctively recognize the wheat from the chaff. Like the bank tellers, this gained by "accurately dividing the Word of Truth"  so that we  "may be able to discern what is best and may be pure and blameless until the day of Christ, filled with the fruit of righteousness that comes through Jesus Christ - to the glory and praise of God. " Phil.1:10 - 11

How is the New Creation (every Christian) like God's First Creation?

1. Both have God as the Author.

"God, who commanded the light to shine out of darkness, has shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ." 2 Corinthians 4:6.

Flavel says, "It is as absurd for any man to say, I make myself to repent or believe, as it is to say, I made myself to exist."

2. The first thing created in both is light. (Gen.1:3)

"And have put on the new man, which is renewed in knowledge after the image of him that created him." Colossians 3:10.

3. Both are created "ex nihilo" - "out of nothing".

Probably everyone here easily believes that God did not need to use preexisting materials for the Creation. There were none, in fact. The analogy continues that God created believers out of nothing in the sense that we did not bring anything of value to Him when  we became saved. We truly "have this treasure in earthen vessels that the excellency of the power may be of God and not of us".  2nd Cor. 4:7

also:

"Who has called you out of darkness into his marvelous light; which in time past were not a people, but are now the people of God; which had not obtained mercy, but now have obtained mercy."1 Peter 2:9, 10

We often hear well-meaning people say, "If only so-and-so would be saved, God could really use his talent of singing (or speaking, etc.)" But this overlooks the fact that God is the one who gives us those gifts of the Spirit for His purpose and in His timing. How can we look at someone before they are even saved and see their spiritual gifts? " 'Not by might nor by power, but by my Spirit,' says the LORD Almighty. "Zech. 4:6

And speaking of the Spirit...

4. Both creations are moved upon by the Spirit of God.

Genesis 1:2 tells us that "the Spirit of God moved upon the face of the waters". The Christ who was present at the creation tells Nicodemus "The wind blows where it wishes"..."So is every one that is born of the Spirit." (John 3:8.) ..."That which is born of the Spirit is spirit." John 3:6.

5. The Word of God spoke both into existence.

"By the word of the Lord were the heavens made; and all the host of them by the breath of his mouth. For he spoke, and it was done; he commanded, and it stood fast." Psalm 33:6, 9.

"Being born again, not of corruptible seed, but of incorruptible, by the Word of God, which lives and remains for ever"1 Peter 1:23.

"Of his own will he gave birth to us by the word of truth." James 1:18

6. Both creations are actively maintained by the "Word of His Power".

John Flavel wrote:

"So it is with the new creation, which entirely depends upon the preserving power which first formed it. "Preserved in Jesus Christ" (Jude 1).  "Who are kept by the power of God, through faith, unto salvation." (1 Peter 1:5). "As we live, move, and have our being in God " (Acts 17:28), so in a spiritual sense we continue believing and delighting in God, without whose continued influence upon our souls we could do neither."

Flavel passes over one of the best verses for this wonderful truth, Colossians 1:17:
"He (that is, Christ) is before all things, and in him all things hold together. "

7. God saw and said that both creations were good. Genesis 1:31 ("very good").

See also Galatians 6:15. If we are in Christ, if we are walking in the Spirit, the Father is pleased with us because we are "accepted in the Beloved".

8. Both creations are groaning in this present age:
" We know that the whole creation has been groaning as in the pains of childbirth right up to the present time.  Not only so, but we ourselves, who have the firstfruits of the Spirit, groan inwardly as we wait eagerly for our adoption as sons, the redemption of our bodies."  (Romans 8:22 - 23)

9. Both will get a total renovation - Praise God!

I hope that this little look at what it means to be a new creation is encouraging to you, and that it will suggest further avenues for studying!